Progressive expansion of p75/AIRM1⁻KIR⁺ and p75/AIRM1⁻NKG2C⁺ NK cells. (A) Freshly isolated NK cells were double-stained with anti-CD56 and anti-p75/AIRM1 mAbs. Three representative donors from groups 1, 2, and 3 are shown at different time intervals after transplantation. (B) For comparison, NK cells isolated from 2 representative healthy adult donors and 1 CB sample are shown. (C-D) Freshly isolated NK cells were double-stained with anti-p75/AIRM1 and anti-KIR (C) or anti-NKG2C (D) mAbs at 1, 3, 6, and 12 months after UCBT. In the lower right quadrant the percentage of p75/AIRM1⁻KIR⁺ and of p75/AIRM1⁻NKG2C⁺ cells is indicated. A representative patient from group1 (top) and one from group 2 (bottom) are shown. (E) The same analysis was performed for NK cells from a patient belonging to group 3, a CB, and 2 healthy donors. In the double fluorescence analyses against NKG2C, a different anti-p75/AIRM1 mAb displaying lower reactivity had to be used for technical reasons.